Due to the proximity and relationship of the temporomandibular joint to the oral cavity, the dental profession has taken the lead in research of these disorders. Accurate diagnosis is however fraught with innumerable problems. This is where imaging plays a pivotal role. The goal of any imaging technique should be to evaluate the integrity and relationship of the structures when disease is suspected and to confirm the extent of the disease. The displacement of disc anterior to the condyle is known as internal derangement. The severity of internal derangement can be graded by evaluating the position and morphology of the articular disc of the TMJ and the hard tissue changes in the bony components of the joint. . This book tries to diagnose this specific disorder of TMJ clinically as well as with the help of MRI which is considered the gold standard in the diagnosis of TMJ internal derangement. We have further tried to correlate the clinical findings with those found on MRI and graded them accordingly. This analysis should help shed some light on the various clinical and MRI characteristics of internal derangement for diagnosis, and timely management of the disorder accordingly.